1. Field
Embodiments of the present invention relate to an oil passage structure for a hydraulic clutch of engines.
2. Description of the Related Art
Japanese Patent Laid-Open No. Hei 7-42761 describes a hydraulic clutch wherein lubricating oil is introduced into a canceler chamber in order to cancel hydraulic pressure which is generated in a control hydraulic chamber under a centrifugal force. This hydraulic clutch includes a clutch piston having an end facing the control hydraulic chamber and the other end facing the canceler chamber.
As shown in FIGS. 1 and 2 of Japanese Patent Laid-Open No. Hei 7-42761, the diameters of a lubricating oil passage and a control oil passage which are defined in a rotational shaft have to be about the same as each other in order to avoid physical interference between the lubricating oil passage and the control oil passage. There is a demand for a lubricating oil passage of increased diameter for supplying a sufficient amount of lubricating oil to lubricated parts.